Abstract:

Zinc ferrite (ZnFe₂O₄) produced in the roasting stage of zinc concentrate is a group of complex oxides with spinel structure, stable in nature and insoluble in dilute acids and bases. Under conventional leaching conditions, 20% of zinc still exists in zinc leaching residue in the form of zinc ferrite, resulting in low zinc leaching rate of zinc concentrate roasting products, generally about 80%. Mechanical activation has the advantage of creating defects in the mineral lattice and reducing the dependence of reaction conditions such as temperature and acid concentration. Therefore, Mechanical activation was used to pretreat zinc calcine using sulfuric acid as the leaching agent. The effects of mechanical activation time, ball-to-material ratio, sulfuric acid concentration, liquid-to-solid ratio and temperature on zinc leaching efficiency and other impurity ions were investigated. The results showed that zinc leaching efficiency increased with increasing mechanical activation time. The leaching results using the mechanical activation (3.60% mass ratio of H₂C₂O₄·2H₂O to zinc calcine, 2∶1 ball-to-material ratio, 10min ball milling time)-acid leaching process indicated that the zinc leaching rate reached 87.61% with 70g/L H₂SO₄ and 10∶1 liquid to solid ratio at 35°C, which was 5% higher compared to that without mechanical activation (82.59%). Mechanistic analysis showed that mechanical activation reduced zinc calcine particle size, resulting in lattice distortion and localized damage. After mechanical activation, the crystallinity of zinc ferrite in zinc calcine decreased from 47.90% to 34.50%, thus the leaching agent penetrate into the zinc calcine particles more easily, promoting zinc leaching. The findings of this paper would provide a new approach to the green and low-carbon development of the electro-zinc industry.

Key words: leaching, activation, zinc calcine, enhanced leaching, zinc

摘要：

锌精矿焙烧阶段产生的铁酸锌（ZnFe₂O₄）是一类具有尖晶石结构的复合氧化物，性质稳定，不溶于稀酸和碱，在常规浸出条件下，仍有20%的锌以铁酸锌的形式存在于锌浸渣中，导致锌精矿焙烧产物的锌浸出率不高，一般为80%左右。机械活化具有使矿物晶格产生缺陷，降低反应对温度、酸浓度等条件依赖程度的优点。因此，本文采用机械活化对锌焙砂进行预处理，以硫酸为浸出剂，研究了机械活化时间、球料比、硫酸浓度、液固比、温度对锌的浸出率及其他杂质离子的影响规律。结果表明：锌的浸出率随机械活化时间的延长呈现出先增大后降低的趋势。机械活化（H₂C₂O₄·2H₂O与锌焙砂的质量比为3.60%，球料比为2∶1，球磨时间10min）-酸浸（70g/L H₂SO₄，液固比为10∶1，温度为35℃）工艺结果表明，锌的浸出率为87.61%，与未机械活化时相比（82.59%），锌的浸出率提高5个百分点。机理分析表明，机械活化使锌焙砂颗粒粒径变小，产生晶格畸变和局部破坏，锌焙砂中铁酸锌的结晶度从47.90%降至34.50%，使得浸出剂更易渗透到锌焙砂颗粒内部从而促进锌的浸出。

关键词: 浸取, 活化, 锌焙砂, 强化浸出, 锌